Background and Aim: Childhood overweight and obesity are becoming a major public health concern all over the world. Change in lifestyles and economic growth have led to sedentary lifestyle and altered dietary patterns. There are conflicting reports in the literature regarding the association between body mass index (BMI) and dental caries from various parts of the world. The aim of the present study was to determine if there is an association between BMI-for-age and dental caries in children and to find out the role of diet with respect to BMI-for-age and dental caries. Materials and Methods: Demographics and anthropometric measurements were obtained for 600 children and BMI-for-age was calculated. Clinical examination for dental caries was carried out following WHO criteria. A diet recording sheet was prepared and children/parents were asked to record the dietary intake for 3 days. Data obtained were statistically analyzed using Chi-square, analysis of variance (ANOVA), and multiple linear regression. Results: After excluding improperly filled diet recording sheets, 510 children were included in the study. Caries prevalence was more in obese children than in other BMI groups. Caries scores increased as BMI-for-age increased, though this was not statistically significant. Consumption of fatty foods and snacks was more with obese children compared to other groups. A correlation was found between caries and snacks. Conclusion: Dental caries scores showed no relationship between BMI-for-age in children. Both snacks and fatty food items were consumed more by obese children, which seeks attention.

Obesity has become an epidemic in many parts of the world. [1] It is not only a problem found in the adult population but has also become an increasing problem of childhood. [2] In India, the problem of obesity has been scantily explored even in the affluent population groups. [3] Obesity appears to influence the general health as well as the oral health of an individual, and particularly in children, it increases the risk of subsequent morbidity, with increased prevalence of hypertension, type 2 diabetes mellitus, dyslipidemia, left ventricular hypertrophy, non-alcoholic steatohepatitis, obstructive sleep apnea, and orthopedic and psychosocial problems, accelerates dental development, and decreases masticatory performance. [4],[5],[6],[7]

Several characteristics of today's society contribute to the widespread childhood obesity problem. Children today lead more sedentary lifestyle. The factors contributing to the increase in childhood obesity include excessive consumption of soda and juice, large-sized portions of food served over the past 10 years, fewer meals eaten together as a family, consumption of fewer fruits and vegetables, dependency on readymade food items, decreased physical activity with great popularity of television and computer games, and shortage of space in many schools for outdoor sports. [8],[9],[10] An increase in energy stored, as fat, can lead to obesity and a number of mechanisms can contribute to an increase in stored energy. If energy intake is in excess of energy expenditure or there is normal intake with reduced expenditure, it results in the disturbance in the energy balance equation and increases the stored energy, resulting in increase in weight or obesity. [11]

The relationship between ingestion of refined carbohydrates, especially sugars, and the prevalence of dental caries is well documented in the literature. One of the etiological factors of obesity is diet which also has an equally important role in the caries process. Not much literature is available to know if there is any direct relationship between obesity and dental caries in children. So, the present study was carried out with an aim to determine if there is an association between body mass index (BMI)-for-age and dental caries in children and to find out the role of diet with respect to BMI-for-age and dental caries.

Materials and Methods

The research was ethically conducted in accordance with the Declaration of Helsinki. The study was approved by the institutional review board and ethics committee of the Ragas Dental College and Hospital, The Tamilnadu Dr. MGR Medical University, Chennai, India. This observational cross-sectional survey was conducted by the Department of Pedodontics and Preventive Dentistry, Ragas Dental College and Hospital, Chennai, among a group of 600 healthy school-going children in Chennai city, between 6 and 12 years of age and of both the genders, for a period of 3 months from January 2011 to March 2011.

Children with the following criteria were excluded from the study.

Children with long-standing systemic illness

Children who were on any medication within the past 2 months

Children with physical or mental disability

Children for whom parental consent was rejected

Study design

The study was conducted in randomly selected private, government-aided, and government schools. Permission from the school authorities was obtained to conduct the study in their schools. Following this, the study design was explained to parents. After obtaining the parents' written consent in local language/English, children were randomly included in the study. All subjects participated as volunteers in the study and examinations were not compulsory. Demographics including age were obtained from school records prior to anthropometric measurements, clinical oral examination, and diet history.

Calculation of body mass index

Height and weight measurements were recorded for all the children who participated in the study. Weight of each child on barefoot was measured to the nearest 0.1 kg using a portable glass electronic personal weighing scale (EB9003L, Ishimura Med Supplies, Matsudo, Japan) which was calibrated before use. Each child was instructed to stand still, with mass equally distributed between feet, until the scale reading stabilized. The reading was then recorded. Height was measured to the nearest 0.1 cm using a stature meter attached to the wall (size 200 cm, Golechha Diagnostics, Chennai, India). For the calculation of BMI, the following formula was used.

The value obtained was then plotted on age- and gender-specific percentile curves given by the Centres for Disease Control and Prevention, and children were categorized into four groups based on their BMI percentiles [12] as follows:

Under weight group children with BMI-for-age less than 5 th percentile

Normal group children with BMI-for-age greater than or equal to 5 th percentile and less than 85 th percentile

Over weight group children with BMI-for-age greater than or equal to 85 th percentile and less than 95 th percentile

Obese group children with BMI greater than or equal to 95 th percentile

Clinical examination

Caries status (deft and DMFT) was recorded based on WHO recommendations. [13] A single trained and calibrated examiner performed comprehensive clinical examination with the assistance of one recorder. Children were made to sit on the chair and examination was conducted under bright daylight. Sterile mouth mirrors, Community Periodontal Index (CPI) ballpoint probes, and a drying tooth device were used to examine the oral cavity and to detect caries. Caries was recorded as present when a lesion in a pit and a fissure or on a smooth surface had an unmistakable cavity, undermined enamel, or a detectably softened floor or wall. Recording of the data was performed by an assistant.

Diet recording

Food groups were divided into rice and cereal group, meat and poultry group, dairy and dairy products group, vegetable and fruit group (four basic food groups), fat and oil group, and snacks for the study purpose. [14] A custom-made diet recording sheet with the most commonly eaten food items and the food groups they belong to was prepared in their vernacular names for clear understanding at the time of recording data. After obtaining anthropometric measurements and caries status, data on dietary intake of children for 3 days including a weekend were obtained by sending the diet recording sheet to parents through school authorities. [15],[16] Children/parents were asked to mark the appropriate food group and time of consumption in the recording sheet each time when anything was eaten. Older children (9 years and above) were asked to fill the diet recording sheet by themselves under parent's supervision, while parents were asked fill the sheet for younger children (children < 9 years of age). From the data obtained, mean intake of food groups was calculated.

Out of the 600 children who initially participated in the study, 90 children did not fill the diet recording sheet properly and so were excluded from the study. The final study population consisted for 510 children.

Statistical analysis

All the data obtained from anthropometric measurements, dental examination, and diet records were tabulated. Descriptive statistics were used to present the data and analysis was carried out using Statistical Package for the Social Sciences (SPSS) version 15. Results on continuous measurements were presented as mean ± SD (95% Confidence Interval). Chi-squared analyses were used to compare baseline demographic variable (gender) between caries prevalence and among BMI-for-age categories. Analysis of Variance was used to find the significance of deft and DMFT according to BMI-for-age and between diet and BMI-for-age categories. Multivariate regression analysis was used to find out the significant correlation of independents with caries. A P value < 0.05 was considered statistically significant.

Results

Sample distribution

Of the 510 samples, 266 (52.15%) were boys and 244 (47.84%) were girls. A total of 113 (22.15%) children belonged to the underweight BMI-for-age category, 249 (48.82%) children belonged to normal BMI-for-age category, 88 (17.25%) children belonged to the overweight category, and 60 (11.76%) children belonged to obese category. Gender distribution of children in various BMI-for-age categories is given in [Figure 1]. There was no statistically significant difference across gender for any BMI-for-age category ( P > 0.05).

Figure 1: Gender distribution of children belonging to various BMI-for-age categories

Among the study population, the overall caries prevalence was found to be 78.6%. A significant number of children were affected with caries ( P = 0.00). Maximum number of caries affected children belonged to obese group, followed by underweight and normal, and the least number was in overweight category [Figure 2]. Gender did not differ across caries prevalence in any BMI-for-age category [Table 1].

The overall mean deft score was 2.06 ± 2.473, and the overall mean DMFT score was 1.025 ± 1.129. Mean caries scores in permanent dentition (DMFT) increased as BMI-for-age increased, while in primary dentition, deft score was more in underweight children than in normal weight children, but deft scores were more in overweight and obese children. Mean scores of rice and cereal food items, meat and poultry food items, fat and oily foods, and snacks gradually increased from underweight children to obese children [Table 2].

The comparison of daily dietary intake of various food groups and caries in primary and permanent dentition among children belonging to various BMI-for-age categories showed a statistically significant difference in the consumption of meat and poultry food items between underweight and overweight categories, with overweight children taking more of meat and poultry items ( P = 0.05), and between underweight and obese categories ( P = 0.05), with obese group taking more of meat and meat products [Table 3]. On comparing dairy products' consumption between underweight and normal BMI children, a statistically significant difference was found ( P < 0.01), with more of dairy products consumed by normal BMI-for-age category children. Comparison of daily intake of fatty foods and oily items showed statistically significant difference between all BMI-for-age categories ( P < 0.05) except between underweight and normal BMI-for-age categories ( P = 0.93) and between overweight and obese categories ( P = 0.21). Fat and oily food items' consumption was more in obese group, followed by overweight, normal, and underweight in a descending order. A statistically significant difference in the daily consumption of snack items was found between all the BMI-for-age categories ( P < 0.05) except between overweight and obese categories ( P = 0.279). Obese group children ate more snacks than children belonging to other BMI-for-age categories. There was no statistically significant difference in the daily intake of other food groups between various BMI-for-age categories ( P > 0.05). There was no statistically significant difference in the mean caries scores (both deft and DMFT) between children belonging to various BMI-for-age categories ( P > 0.05).

Table 3: Comparison of mean daily dietary intake and caries score of primary and permanent dentition among children belonging to various body mass index-for-age categories

When compared to children in normal BMI-for-age, caries showed no statistically significant relation to underweight, overweight, or obese categories ( P > 0.05) [Table 4]. A significant relation was observed between caries and consumption of snack items ( P < 0.01). No significant relation was found between caries and any other food group (P > 0.05).

Childhood overweight and obesity are global problems that are on the rise due to modernization and change in lifestyle. [17] Childhood obesity and childhood dental caries are coincidental in many populations, probably due to the common confounding risk factors such as intake frequency, cariogenic diet, and poor oral health. [6] Despite many alarming findings, health professionals in both medicine and dentistry have been slow to implement clinical protocols to aid in the diagnosis and treatment of childhood overweight/obesity. [18] This may be due in part to the sensitive nature of the weight-related matters, but it has been shown that health professionals also may lack self-efficacy, knowledge, and information needed to properly diagnose and address the problem. [19] As the obesity epidemic escalates, it is apparent that screening solely during well child visits may no longer be a viable strategy for addressing the issue, and dentists can play a role in handling this problem as children can visit the dentists at the earliest age of 1 year or below and they can also help by providing diet counseling and anticipatory guidance to the parents. Even though the role of dentists is small compared to the physicians, this small success, however, can make a significant difference on a population level. [20]

Children's dietary habits are significant contributors to childhood obesity and dietary imbalance causes dental caries which is well established in the literature. [21] Obesity and malnutrition represent opposite extremities on the spectrum of adiposity, and both are routinely quantified in terms of weight and height relative to the child's age. The most convenient and commonly used tool to screen for overweight/obesity is the BMI (kg/m 2 ), a measure of body weight adjusted for height. Due to differential changes in height and weight during growth and development, BMI percentiles specific for age and sex are used to describe childhood weight status. The Centers for Disease Control and Prevention have published standardized BMI charts to determine BMI percentiles for children. [12] Any weight category other than "healthy weight" (5 th -84 th percentile) as well as a rapidly rising BMI growth trajectory may be a cause for concern and discussion among the health providers, parents, and patient.

The prevalence of overweight in the present study (17.25%) is supported by a finding and more than another finding conducted in India. [22],[23] It is worth mentioning that the calculated global prevalence of overweight (including obesity) in children aged 5-17 years is estimated by the WHO, International Obesity Task Force (IOTF) to be approximately 10%, but this is "unequally distributed." [24]

In the present study, overall caries prevalence was 78.6%. The results of this study are slightly higher than few other findings in the literature. [25],[26] Maximum number of children affected by caries belonged to obese category, followed by underweight category and normal BMI-for-age category, and the least number of children affected by caries belonged to overweight category. Contrary results have also been reported in the literature. [27]

The present study findings showed an increase in mean deft and DMFT scores from underweight BMI-for-age children to obese children, with exception of higher caries scores in primary dentition in underweight children than in normal BMI-for-age children and overweight children. This result is supported by previous findings. [6],[28] In the present study, caries scores gradually increased in both primary and permanent dentition as BMI increased, which shows an association between BMI-for-age and caries, but this was not at a statistically significant level. While few studies showed a positive association between caries and BMI-for-age, [6],[26],[28],[29] some other studies showed no relationship between dental caries and BMI-for-age. [25],[27],[30],[31],[32]

In the present study, the mean scores of all the food groups increased from underweight to obese group except for dairy group and vegetable and fruit group. Except for the underweight group children (who ate more rice and cereals than other food groups), children belonging to all other BMI categories consumed more snacks compared to other food groups, which seeks attention.

A significant difference in the intake of meat and poultry items was seen between underweight and overweight children, and underweight and obese children. There is suggestion in the literature that protein intake, not fat intake, may be associated with the development of adiposity in childhood. It has been proposed that a high protein intake during early childhood stimulates insulin-like growth factor 1 production, thereby triggering precocious adipocyte multiplication. [33]

In the present study, fatty food consumption was found to more in obese group followed by overweight, normal, and underweight groups in a descending order. Also, comparison of daily intake of fatty and oily foods showed significant difference between BMI-for-age categories except between underweight and normal BMI-for-age categories and between overweight and obese categories. So, it can be assumed that children with high BMI values consume more of fatty foods than children with normal or low BMI. Fatty foods, which can be assumed to play a vital role in contributing to the body mass or obesity, were found to be consumed more by obese children than by children in any other BMI-for-age category. Obese category children consumed more snacks, followed by overweight, normal, and underweight children in a descending order. It has been reported in literature that children who were obese and overweight preferred sweet and fatty foods more frequently compared to children with normal weight. [28] It is evident that the deposition of excess adipose tissue results from a positive energy balance. However, a significant body of research findings suggests that the macronutrient composition of the diet affects the composition of human body. In particular, it appears that the proportion of fat ingested, compared to carbohydrates and proteins, influences the amount of body fat. The greater energy density of lipids (38 kJ/g), as opposed to 17 kJ/g for other macronutrients, may be one way in which fat exerts its obesity promoting effect. Thus, a higher fat diet necessarily results in a higher energy intake, which leads to a positive energy balance if the energy expenditure is not increased proportionately. [34]

A balanced diet helps in the development of a healthy child. It should be noted that a proper diet should include all the essential nutrients in adequate quantities. In the modern society, people eat more of fast foods outside home; the frequency of snacking as well as the contribution of snacks to the total caloric intake has drastically increased. Drinks rich in free sugars increase the overall energy intake by limiting the appetite control. Thus, there is less of compensatory reduction of food intake after the consumption of high sugar drinks than when additional foods of equivalent energy content are provided. [28] Few other factors may contribute to the increase in body weight. They include excessive consumption of soda and juices, larger-sized proportions of food served, fewer meals eaten together as a family, consumption of fewer fruits and vegetables, watching television for more hours, and preference of computer games over outdoor sports.

The present study is an attempt to find if there is any relationship between BMI and dental caries and the role of diet in contributing to both the problems. It should be remembered that the concept of biological plausibility suggests that neither the hypothesis "obesity increases risk of caries" nor "caries increases the risk of obesity" is particularly logical. Rather, it is more realistic that a common risk factor increases the likelihood of both diseases, which are then observed in association. [35]

Both obesity and dental caries are complex issues with multiple etiological factors. Our analysis was limited to dietary pattern alone which is only one of the causative factors common to both dental caries and obesity. Within the limitations of the present cross-sectional survey, a cause-effect relationship over a limited period of time could not be established. Only qualitative and not quantitative analysis of diet was done in our study. As most of the diet taken by Indians is custom made, it is difficult to assess the calorific value of such diet which might give an exact picture about the diet's influence on body weight.

Conclusion

The assumption that "overweight/obesity correlates with more caries" cannot be statistically proven in this study though caries scores in both the dentitions increased as BMI-for-age increased. Further studies should be targeted on exploring other contributing factors to obesity like physical activity, genetic makeup of the child, and caloric quantification of dietary intake on a larger scale.

Our world is in the midst of a childhood obesity crisis that threatens its long-term health. It is easy to speculate that we are only seeing the tip of the iceberg and that the future economic, health, and social consequences of childhood obesity may be one of the world's most serious challenges in this century. As members of the dental health team, it is critical that dentists maintain awareness of this problem and participate in the assessment and prevention of childhood obesity.